Physics LOI for NEDA Valencia 4 November 2010 R. Wadsworth University of York, G. de Angelis INFN...

Physics LOI for NEDA

Valencia 4 November 2010

R. Wadsworth University of York , G. de Angelis INFN LNL

NEDA LOI Istanbul 19 june 2009

SPES LOI LNL 15 november 2010

LOI SPIRAL2 Phase 2 17 December 2010

Spes – LNL Radioactive Ion Beam Spes – LNL Radioactive Ion Beam FacilityFacility

Radioactive beams of species with lifetimes in excess of several days can be efficiently generated by irradiating target materials with a 40-50 MeV proton beam for a time sufficiently long for secular equilibrium to transpire followed by a transfer of the target to the ion source (Batch Mode).

• Particles: H- / D- / He2+/ HH+

• Variable Energy : 15 MeV 70 MeV

• Performances: 750µA H- 70MeV 35µA He2+ 70MeV

Light RIBs at SPES

• A/Z t1/2(s) A/Z t1/2(s) • 6He 3.0 0.81 9Be(n,) 8B 1.6 0.77 12C(p,n)• 8Li 2.7 0.84 11B(n,) 10C 1.7 19.3 11B(p,2n)• 9Li 3.0 0.18 11B(n,3He) 11C 1.8 1224 11B(p,n)• 11Be 2.8 13.8 11B(n,p) 13N 1.9 598 13C(p,n)• 16N 2.3 7.13 16O(n,p) 14O 1.8 70.6 14N(p,n)• 18N 2.6 0.62 18O(n,p) 15O 1.9 122 15N(p,n)• 19O 2.4 26.9 19F(n,p) 18Ne 1.8 1.67 19F(p,2n)• 20O 2.5 13.5 19F(n,) 19Ne 1.9 17.3 19F(p,n)• 23Ne 2.3 37.2 24Mg(n,2p) 35Ar 1.9 1.77 35Cl(p,n)• 25Ne 2.5 0.60 26Mg(n,2p) 34Ar 1.9 0.60 35Cl(p,2n)• 25Na 2.3 59.1 25Mg(n,p)• 26Na 2.4 1.08 26Mg(n,p)

Halo nuclei

44Ti

44Sc

44Ti

t1/2=60 y

t1/2=3.92 h

44Ca11

57

+

+

Batch mode

Target: monoisotopicReaction: 45Sc(p,2n)

68Ge

68Ga

68Ge

t1/2=288 d

t1/2=68.3 m

68Zn10

77

+

+

Target: natural GaReaction: 69,71Ga(p,2,4n)

Batch mode

82Sr

82Rb

82Sr

t1/2=25.5 d

t1/2=1.27 m

82Kr77 6

+

+

Target: naturalReaction: 85,87Rb(p,xn)

Contaminationfrom 85Sr

Batch mode

natRb natGa Ag

Water flow ~ 1L/s

I = 350 A 55 MeV

I = 350 A 20 MeV

Multi-target production

Parallel 82Sr (p6n), 68Ge (p,4n) and 44Ti(p,2n) production

Silber orCopperbacking

plateL=2mm

350 A proton beamto be dissipated:

70 MeV

24000 W

Water coolingL=10mm

Target layer0.86 mm

Beam area0.78 cm2

Cooling Area 1 cm2

Assuming Twater=200

Sc melting point 15390

Qconv= hA(T1-T2) or h = Q/[A(T1-T2)]

h = 24000 W/(1cm2) (900-20C) = 27.3 Wcm-2C-1

Film Heat density to be removed

Discontinuity among layers neglected

Water cooling

Laminar flow Re 1000 Turbulent flow Re 5000

Turbulent flow more effectiveIn removing heat:Net mass transfer

Prandtl number: Pr=Cp/k Cp heat capacity viscosity k thermal conductivity

Nusselt number: Nu=hx/k h film heat density x significant distance

Ratio between viscous to the heat transfer properties

Ratio between heat transported by convection and heat transported by conduction

Reynolds number: Re=xV/ V velocity of the bulk fluid

Ratio of inertial forces to the viscous forces

Thermal water conditions• Nu=hx/k=27.3x1/0.00604=4520

kwater=0.00604 W cm-1K-1

• Pr=Cp/k=4.179 x 0.8513/0.0604=58.9water=0.008513 gcm-1s-1

• Nu=0.332 Re1/2Pr1/2 Re=xV/=3.15 106

V = 2.7 104 cm s-1 If internal volume =0.5 x 2 cm2

water flux 27 L/s too much!

Reduce volume of the cooling water (increase the flow velocity) and increase surface area (incline the target to beam)

=780 L=5 Volum 0.2 cm2 Flux1,1 L/s

Heat Transfer from Ag/Cu layer• Qcond= -kA(T1-T2)/x

T1-T 2= Qx/kA =24000x0.2/[4.03x1cm2]= 1191K 900 C

=780 T1-T2= Qx/kA = 24000x0.2/[4.03x5] = 238 K

Maximum cross section (p,2n) at 20 MeV Q = 20 x 350 = 7000 W

• Qcond= -kA(T1-T2)/x

T1-T2= Qx/kA = 10500x0.043/[0.31x1cm2] = 1456K1160 C

=780 T1-T2= Qx/kA = 10500x0.043/[0.31x5] = 291 K

Heat Transfer from target layer

kAg,Cu=4.03 Wm-1C-1

kTi=0.31 Wm-1C-1

Silverbacking

plateL=2mm

=780

45Sc0.2 mm

Ag (Melting point 1235 K)

Water flow ~ 1L/s

Cross section45Sc(p,2n)

32 mb at 22 MeV(Phys. Rev. C 54, 2047 (96))

63 mb at 30 MeV(Nucl. Phys. A150, 11 (70))

I = 350 A

Q(t)=(6.022 1023 /A) x h x x I = 3.6 1011 atoms/sFor 10 days irradiation t1/2 = 60 y

N = Q/(1-e -t ) = 3 1017 atoms 44Ti corresponding toI=108 atoms/s without chemical separation.

44Ti production

Chemical separationprovided by the productionof radioisotopes

RIB in batch mode

• 9Be(p,p2n)7Be (53.2 d)

• 46Ti(p,p2n)44Ti (63 y)

• 58Ni(p,p2n)56Ni (6.1d)

• 70Ge(p,p2n)68Ge (288 d)

• 74Se(p,p2n)72Se (8.5 d)

• 84Sr(p,p2n)82Sr (25.5 d)

• 90Zr(p,p2n)88Zr(83.4 d)

Intensities ~ 107-109

Defining the Physics• Nuclear Astrophysics

– Element abundances in the Inhomogeneous Bib Bang Model (Weizmann, Soreq, GANIL, York collaboration)

– Isospin effects on the symmetry energy and stellar collaps

• Nuclear Reactions– Level densities of neutron rich nuclei (Naples,

Bordeaux, Debrecen, LNL, Florence collaboration)– Fission dynamics of neutron-rich intermediate fissility

systems• Nuclear Structure

– Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd

– Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states

– Coulomb Energy Differences and Nuclear Shapes– Low-lying collective modes in proton rich nuclei

rapid proton capture,

Reaction Paths in Nuclear Astrophysics

Nuclear Astrophysics : Element abundances in the Inhomogeneous Bib Bang Model

(Weizmann, Soreq, GANIL, York collaboration)

Letter of Intent for the proposed “Neutron Wall” at SPIRAL-II

Measurement of the 8Li(,n) 11B ReactionMichael Hass

for theWeizmann-Soreq-GANIL-York collaboration

We propose to study the 4He(8Li,n)11B reaction using 8Li beams at SPIRAL-II. The R&D efforts to produce unsurpassed intense beams of 8Li at SPIRAL-II may result in 8Li very well becoming one of the first radioactive beams to be used at SPIRAL-II. This fact, together with the unique performance of the proposed neutron wall and of other ancillary charge-particle detectors will provide an ideal experimental setup for such studies. The data thus obtained should clarify the poorly known cross section for this reaction, which is important for several scenarios in the field of explosive nucleo-synthesis.

Michael Hass - 8Li(,n)11B

Fig. 1 Experimental data available in the literature

Fig. 2 States in 12B that are in the region of interest for cosmological (and stellar) environment(s) at temperatures of ~ 1 GK

Michael Hass - 8Li(,n)11B

Expected Yields for a BeO target:SARAF (40 MeV, 2 mA): 8∙1012

[6He/sec]SPIRAL2 (40 MeV, 5 mA): 2∙1013

[6He/sec]

Expected Yields for a BN target:SARAF (40 MeV, 2 mA): 2∙1012

[8Li/sec]

SPIRAL2 (40 MeV, 5 mA): 5∙1012 [8Li/sec]Michael Hass - 8Li(,n)11B

11B

Under current R&D:

• Diffusion and effusion in the material• Ionization and extraction• Choice of ion source

11B(n,a)8Li5 1012 pps

Fig. 3 The proposed experimental setup.

Issues for consideration

• 8Li@SPIRALII The present scheme uses the 11B(n,a)8Li reaction with secondary neutrons from the initial 5 mA, 40 MeV d beam with a porous BN target. Post-acceleration. Energy degrader.

• The neutron wall

• Charge particle (11B) detection

Michael Hass - 8Li(,n)11B

Neutron (energy) + charge particle detections

Why is it important to study the symmetry energy ?

Esym=bsym(T)(N-Z)2/A

• As a part of the nuclear Equation Of State it may influence the mechanism of Supernova explosion

• General theoretical agreement on its temperature dependence (LRT+QRPA vs. large scale SMMC)

• Possible consequences of T dependence of Esym on core-collapse Supernova events

• Effects enhanced by the instrinsic isospin dependence of Esym

Fusion-evaporation reactions: Esym affects the particle B.E.

(Naples, Debrecen, LNL, Florence collaboration)

Isospin effects on the symmetry energy and stellar collapse

A. Di N

itto

SYMMETRY ENERGY

m(T) 0 < T < 3 MeV - 98Mo, 64Zn, 64Ni

-LRT – QRPA

Decrease of the effective mass Increase of Esym

Esym(T)= bsym(T) x (N-Z)2/A

bsym(T)=bsym(0)+(h2ko2m/6mk)[m(T)-1 – m(0)-1]

m(T)=m + [m(0) – m]exp(-T/To)

Framework: Dynamical ShellModel

Hartree-Fock Coupling single particle statesto suface vibrations

Nucleon effective mass

m

mmm k

A. Di N

itto

Nuclear Reaction Mechanisms:

Evaporative neutron emission as a probe for the level density of hot neutron-rich compound nuclei (Naples, Bordeaux, Debrecen, LNL, Florence collaboration)

Neutron energy and multiplicity information + Charged particle information + gamma ray information

A. Di N

itto

0 1 2 3 4 5 6

100

101

102

103

Co

un

ts

En,cm(MeV)

Standard N-Z Z-Zo

0 1 2 3 4 5 6

100

101

102

103

Co

un

ts

En,cm (MeV)

Standard N-Z Z-Zo

Isospin effects on the level density parameter aStudy with RIB’s from SPIRAL2

A strong sensitivity on isospin is also expected for the evaporation residue yields

Experimental setup: NEDA coupled to the gamma ray spectrometers EXOGAMor AGATA and/or the spectrometer VAMOS. (NEDA: TOF Measurements 3% resolution, energy threshold 1 MeV). Lcp could be also measured by Diamant.

84Ge + 4He

134Sn + 4He

n

n

Observables

- xn channels)

- n en. spectra

- ER yields

A. Di N

itto

Fission dynamics of neutron-rich intermediate fissility systems (under study)

Open questions in fission dynamics: Fission delay, nature of dissipation (one or two body) and its dependence on temperature and nuclear deformation

Systems of intermediate fissility (A 150): possibility to measure observables in both fission and evaporation residue channels

Fission BarrierBf (L=50 )

(MeV)

n- Prescissionmultiplicity

Mn

Fission time <Tfiss>

(10-21 s)

124Ce 16.3 0.046 61

144Ce 29.7 2.1 103

Measurements on nuclei with the same Z and different isospin allow to Study of the role of isospin in fission dynamics:

230 MeV 32S + 92Mo Lcrit = 74 750 MeV 118Pd + 26Mg Lcrit = 81 Ex122 MeV

Preliminary results from a dynamical model based on three dimensional Langevin equations

Experimental setup: NEDA coupled to fission fragment detectors

A. Di N

itto

Nuclear Structure : N=Z nuclei

Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd

Coulomb Energy Differences in isobaric multiplets: T=0 versus T=1 states

Coulomb Energy Differences and Nuclear Shapes

Shape phase transitions in nuclei

Nuclear structure in the 100Sn region (batch mode)

Low-lying collective modes in proton rich nuclei

G. de France

A. Gottardo, M. Palacz

A. Pipidis

Probe of the T=0 correlations in N=Z nuclei: The structure of 92Pd

(LNL, Stockholm, York collaboration)

Neutron multiplicity information + charged particle + gamma ray information

G. de France

G. de France

Coulomb Energy differences in isobaric multiplets: T=0 versus T=1 states

(Sofia, Padova, York, Ganil, LNL collaboration)

Neutron multiplicity ( and energy) information +Charged particle + gamma ray informations

Need for an Isospin Breaking NN term

Description of Coulomb effects

CmCMC VVV

Multipole term

Monopole term Vcm= εll + εls + VCr

Coulomb contribution between valence protons

Radial term: radius R changes with J

orbital single-particle shift for proton

spin-orbit single-particle shift (EM pot.)

l.s

dr

dV

rcmgg C

Nlsls

1

4

1)(

22

keVNA

NNllZcsll )2/3(

)]3()1(2[5.43/1

12/13

R

ZZeVCr

)1(

5

3 2

Zuker et al,(2002)Ekman et al, (2004)Bentley,Lenzi, (2007)

VCM

VCr

εll

εls

Shell model calculation

Spin alignment

Isospin Breaking NN term in the fp region

fpg mass region

R. Orlandi et al., PRL103,052501(2009)

As)(E*Se)(E*MED 6767JJJ

Coulomb and isospin nonconserving NN interaction break charge symmetry

Mirror Energy Differences (MED)

D. G. Jenkins et al., PRC64,064311(2001)G. de Angelis, Prog. Part. Nucl. Phys. 59, 409 (2007)

Good charge symmetry ?

MED

orbital

spin-orbit

radial

multipole

Apparently no need of an Isospin Breaking NN term in the fpg shell!

Example: Electromagnetic Transition Probabilities

If Isospin Symmetry is valid:

E1 (T=0) transitions in N=Z nuclei are forbidden

E1 transition in mirror pairs have identical strength(higher sensitivity due to interference)

Crucial Probe of the isospin symmetry and of its validity with increasing A and Z

Observation of a forbidden E1 transition in 64Ge

64 32 32

64Ge

EUROBALL IV + Plunger experiment

E. Farnea et al. Phys. Lett. 551B, 56 (2003)

forbidden E1?

32S+40Ca 125 MeV

Electromagnetic Transition Probabilities

Dobaczewski and HamamotoPhys. Lett. B345 181 (1995)

Dobaczewski and HamamotoPhys. Lett. B345 181 (1995)

Isospin mixing via the IVGMR provides an induced isoscalar component

In mirror T=0 transitions• Isovector terms have opposite sign • Isoscalar terms have equal sign

B(E1) = BIS(E1) – BIV(E1)

J. Ekman et al. PRL 92, 132502 (2004)

B(E1) strengths are identical in T=1/2 mirror pairs

B(E1) = BIS(E1) + BIV(E1)

Isospin Mixing in Mirror Pairs

In the validity of isospin symmetry

1) Charge invariance of the nuclear interaction

2) Long-wavelength approximation

N=Z nuclei: Reactions with RIBS

• 34Ar (108pps) + 40Ca (105-120 MeV)– 69Br + p 1 mb – 71Kr + 2pn 5 mb– 68Br + pn 0.2 mb– 72Rb + pn 0.1 mb

• 58Cu + 28Si (~200 MeV)– 81Nb + n 0.1 mb

• 56Ni + 28Si (~200 MeV) – 79Zr + n 0.2 mb

Coulomb Energy Differences and Nuclear Shapes

(York, LNL, Padova, Sofia collaboration)

Neutron multiplicity information, charged particle and gamma information

N = ZN = Z Nuclei and Mirror Symmetry Nuclei and Mirror Symmetry

In reality

According to the Pauli principle

protons and neutrons behave identically

Only strong interaction

Z

Z+1

Z-1

Z+½

Z-½

N=ZT = 1/2 Mirrors exchange the valence proton and neutron.

T = 1 Mirrors exchange two valence protons and neutrons on both sides of a odd-odd N = Z.

N=Z

35

36

35 36

70Br

34

34

70Se

70Kr

Shape Coexistence in Mass 70Shape Coexistence in Mass 70

oblate prolate

74Kr

M. GirodM. Bender et al., PRC 74, 024312 (2006)

Prolate ground state

Shape effects

G deAngelis et al., to be publishedGAMMASPHERE, Neutron shell, Microball: 40Ca(32S,αpn) @ 90 MeVTarget: 550μg/cm2 on 10mg/cm2 Au

66As66As data suggests that A=70 CED data is unique !

Shape effectsExcited VAMPIR Model (A Petrovici et al Nucl Phys A483, 317 (1988))

Beyond mean-field approach with symmetry projection

Successfully used to describe analogue states in mass 70 region, Petrovici et al., Nucl Phys A728, 396 (2003)

Takes into account:Oblate/ prolate shape co-existencen-p pairing correlations in both the T=0 and T=1 channels

Calculations performed using the isospin symmetric G matrix based on Bonn A potential and Coulomb interaction between the valence protons.

Shape effects SPIN

Nucleus Wavefn 0+ 2+ 4+ 6+

66As Obl(Prol) 16(84) 30(70) 19(81) 5(95)

66Ge 20(80) 39(61) 33(67) 9(91)

70Br 36(64) 41(59) 41(59) 20(80)

70Se 57(43) 59(41) 64(36) 39(61)

For the A=82,86 nuclei a prolate component dominates for all yrast states with amplitude >90% A Petrovici, J Phys G37 064036 (2010)

For isobaric triplets, generally assumed that the nuclei have identical shape. Calcs suggest this may not be true for the mass 70 systems!

Calculations by

A Pertrovici

Coulomb Excitation of Coulomb Excitation of 7070Se at REX-ISOLDESe at REX-ISOLDE

70Se on 104Pd at 2.94 MeV/u integral measurement excitation probability via normalization to known 104Pd

A.M. Hurst et al., PRL 98, 072501 (2007)

P2+ is function of transitional matrix element B(E2) diagonal matrix element Q0

If

Ii

Mf one measurement, but two unknowns !

Lifetime of the 2Lifetime of the 2++ state in state in 7070SeSeMarch 2007GASP and Köln Plunger at Legnaro

40Ca(36Ar,2p)70Se40Ca(36Ar,4p)72Se

[1] J. Heese et al., Z. Phys. A 325, 45 (1986)[2] J. Ljungvall et al., PRL 100, 102502 (2008)

old [1]

(ps)

new [2]

(ps)

B(E2;) (e2fm4)

70Se

2+ 1.5(3)

3.2(2) 342(19)

4+ 1.4(3)

1.4(1) 370(24)

6+ 3.9(9)

1.9(3) 530(96)

ConsequencesConsequences

new lifetime measurementJ. Ljungvall et al. PRL 100,102502 (2008)

Prolate

Oblate

lifetime measurement

= 1.5(3) ps

J. Heese et al., Z. Phys. A 325, 45 (1986)

)65(615.00)2(2 11 EM

*

Lifetime measurements in the other members of the isobaricmultiplet: 70Br, 70Kr

N=Z nuclei: Reactions with RIBS

• 34Ar (108), 30S (107)+ 40Ca (105-120 MeV)– 70Br, 65As + 3pn 1 mb – 71Kr, 67Se + 2pn 5 mb– 68Br, 64As + pn 0.2 mb– 72Rb, 68Br + pn 0.1 mb

• 58Cu + 28Si (~200 MeV)– 81Nb + n 0.1 mb

• 56Ni + 28Si (~200 MeV) – 79Zr + n 0.2 mb

A=64, 68 T=1 triplet

Nuclear Structure :Low-lying collective modes in proton rich nuclei

Valencia, INFN LNL , Paris, INFN MI collaboration.

Neutron multiplicity (and energy), charged particle and High energy gamma information

34Ar + 16O 44Cr + 2n

34Ar 108 pps

Dipole Excitations towards the Proton Drip-Line

CENTROID ENERGY OF THE LOW-LYING STRENGTH

CENTROID ENERGY OF THE LOW-LYING STRENGTH

LOW-LYING TRANSITION STRENGTH B(E1)

LOW-LYING TRANSITION STRENGTH B(E1)

PROTON PYGMY DIPOLE RESONANCE

PROTON PYGMY DIPOLE RESONANCE

Paar, Vretenar, Ring, Phys. Rev. Lett. 94, 182501 (2005)

Dipole Excitations towards the Proton Drip-Line

CENTROID ENERGY OF THE LOW-LYING STRENGTH

CENTROID ENERGY OF THE LOW-LYING STRENGTH

LOW-LYING TRANSITION STRENGTH B(E1)

LOW-LYING TRANSITION STRENGTH B(E1)

PROTON PYGMY DIPOLE RESONANCE

PROTON PYGMY DIPOLE RESONANCE

Paar, Vretenar, Ring, Phys. Rev. Lett. 94, 182501 (2005)

24Mg(p,p2n) 22Mg

22Mg + 16O 32Ar + 2n 22Mg 108 pps

Isobaric Analog - Spin-Isospin resonances and the neutron distribution in the Sn isotopes

The predicted reduction in the spin-orbit term in the nuclear force with increasing neutron excess is believed, together with the tensor component of the residual nucleon nucleon interaction, to be the main origin of the changes in the single particle energies of intruder states and of the shell quenching effects.

Valencia, LNL, Saclay

Difference in slope between of the neutron and proton density distributions through the excitation energies of the Gamow-Teller resonances relative to the isobaric analog states. Nucleons with spin-up and spin-down oscillate either in phase (spin scalar S=0 mode) or out of phase (spin vector S=1 mode). The spin vector, or spin-flip excitations can be of isoscalar ( S=1, T=0 ) or isovector ( S=1, T=1 ) nature. The Gamow-Teller resonance is the collective spin-isospin oscillation with the excess neutrons coherently changing the direction of their spin and isospin without changing their orbital motion (GTR) Jp=1+. The Isobaric Analogue State does not require the spin-flip ( i.e. S=0 ) ( IAS ) Jp=0+. The Wigner SU(4) symmetry implies the degeneracy of the GTR and IAS. It is broken by the spin-orbit term of the effective nuclear potential.

Charge exchange reactions in inverse kinematics (p,n) with RIB for different isotopic chains:Es. neutron rich Sn isotopesResonance energy from the neutron spectrum, 5%-10% energy resolution should be sufficient

Thanks for attention

• Present LOIs still under development

• Please join LOIs or present new ones

• Upgrading of the physics case is on the way (following presentations)

• Definition of the “day one” experiments